U.S. patent application number 13/732279 was filed with the patent office on 2014-07-03 for detection and display of measured subsurface data onto a surface.
The applicant listed for this patent is Jonathan Thierman. Invention is credited to Jonathan Thierman.
Application Number | 20140187966 13/732279 |
Document ID | / |
Family ID | 51017984 |
Filed Date | 2014-07-03 |
United States Patent
Application |
20140187966 |
Kind Code |
A1 |
Thierman; Jonathan |
July 3, 2014 |
Detection and Display of Measured Subsurface Data onto a
Surface
Abstract
The present disclosure provides systems and methods for imaging
and display of subsurface features of a region of interest such as
a portion of a body of a patient. A first imaging portion of the
system is used to cause an interaction of an imaging beam with an
underlying feature of a region of interest. A retro-reflected or
returned portion of said imaging beam is detected by a detector
which then provides an output to control a display portion of the
system for displaying an image corresponding to that which was
detected. The system can be used for guiding or assisting clinical
or industrial operations or for diagnosis of medical conditions and
other uses within medicine, industry and others.
Inventors: |
Thierman; Jonathan;
(Baltimore, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Thierman; Jonathan |
Baltimore |
MD |
US |
|
|
Family ID: |
51017984 |
Appl. No.: |
13/732279 |
Filed: |
December 31, 2012 |
Current U.S.
Class: |
600/473 |
Current CPC
Class: |
A61B 5/0059
20130101 |
Class at
Publication: |
600/473 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1. An imaging system for imaging a subsurface region of interest,
comprising: a plurality of coherent light sources; an optical
assembly that spatially scans respective outputs from said
plurality of coherent light sources onto a surface of the region of
interest; a first coherent light source providing light of a first
wavelength of the electromagnetic spectrum that penetrates the
surface to interact with a first kind of structure beneath said
surface, a portion of said light at said first wavelength then
returning to a detector of said light of said first wavelength; a
second coherent light source providing infrared light at a second
wavelength, longer than said first wavelength, said infrared light
also penetrating the surface to interact with a second kind of
structure beneath said surface, a portion of said infrared light
then returning to a detector of said infrared light; a signal
processing unit receiving a first signal corresponding to said
returned portion of said first light and a receiving a second
signal corresponding to said returned portion of said infrared
light, said signal processing unit generating an output indicative
of a sensed condition beneath said surface determined at least by
both of said first and second signals received corresponding to the
returned first light and returned infrared light; and a display
light source emitting a visible display signal projected onto said
surface of the region of interest corresponding to the sensed
condition as a function of position on said surface of the region
of interest.
2. The system of claim 1, said first light of first wavelength
corresponding to light in the red portion of the electromagnetic
spectrum.
3. The system of claim 1, said plurality of coherent light sources
comprising laser light sources including at least two such sources
providing respective wavelengths that are absorbed by oxygenated
hemoglobin (HbO2) and non-oxygenated hemoglobin (Hb),
respectively.
4. The system of claim 3, said first wavelength being absorbed by
non-oxygenated hemoglobin (Hb) and having a wavelength between 500
and 800 nm.
5. The system of claim 3, said infrared wavelength being absorbed
by oxygenated hemoglobin (HbO2) and having a wavelength between 800
and 1100 nm.
6. The system of claim 1, further comprising machine readable
instructions for generating pulsed outputs of said first light
wavelength and said infrared wavelength so as to reduce or cancel
background noise artifacts to improve signal to noise output.
7. The system of claim 1, further comprising machine readable
instructions for outputting readable characters indicating any of:
percent oxygenation of a patient's blood, patient's heart rate and
a temperature map of the patient's region of interest.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation in part and claims
the benefit and priority of U.S. patent application Ser. No.
11/854,866, bearing the title "Compact Feature Location and Display
System", filed on Sep. 13, 2007, which is hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present disclosure relates to imaging and visualization
of features below the surface of an opaque object, for example
blood vessels in tissue, and specifically in some instances to
non-invasive subsurface measurements and display of the same
information onto the surface.
BACKGROUND
[0003] The human body is supplied by a complex network of blood
vessels as part of the vascular system. The blood vessels are fluid
conduits allowing for flow and distribution of blood throughout the
body, and are generally arranged into arterial and venous
sub-systems, which are themselves hierarchically arranged from
larger ma supply vessels down to small capillary pathways. A
primary function of the blood flowing through the vessels is to
carry and distribute oxygen and other nutrients to the organs and
tissue of the body. Another function of the blood is to collect
waste products from the organs and tissue. Mechanically, the
general organization of the vascular system is that of a hydraulic
supply and return network with the heart providing the pumping and
control to drive oxygenated blood to the organs and tissue in
arteries, and to return blood from the organs and tissue in veins.
Capillaries form the lowest functions on the hierarchy of
vasculature, including the actual chemical (oxygen) exchange, and
connect the arterial portion of the vascular network with the
venous part of the vascular network.
[0004] As it carries oxygen, nutrients and waste products within
the entire body, the vascular system has been recognized as a good
vehicle for introducing drugs into the body, and as a good vehicle
for extracting meaningful (blood) samples representative of the
condition of the body. Since many primary vessels run slightly
below the surface of the skin, they are accessible for procedures
to introduce a substance into the blood or to extract a sample of
blood from the vessels. For example, a common procedure is to
introduce a drug or a fluid into the blood stream intravenously
using an intravenous ("IV") line. Glucose and antibiotics are
examples of things commonly injected into a patient's veins using
an IV line. In practice, a medical professional inserts a needle
through the skin and through one wall of a relatively large and
accessible vein and the injected fluid is released into the vein
through the IV needle under pressure. The converse (blood sampling)
is used by pulling blood from a vein, or allowing the blood to flow
out of the vein and into the needle, to draw a blood sample from a
patient these procedures can be painful to people, as they involve
sticking the patient with a needle. Also, inaccurate placement of a
needle can lead to improper delivery of the drug or fluid, and can
cause unwanted injury to vessels and tissue in the vicinity of
vessels. It is therefore preferable that the needle be inserted
accurately and hit its mark without undue retries. The present
discussion of veins can where applicable be extended to other types
of fluid vessels, for example, arteries, capillary vessels,
etc.
[0005] One type of clinical procedure using the location of the
appropriate vessels is the insertion of a central line, also called
a central venous catheter ("CVC"). A central line is a catheter, or
tube, which is inserted into a vein and physically passed through
the vein to the thoracic (chest) portion of the vena cava or the
right atrium of the heart. The vena cava is a large vein delivering
blood to the heart. Again, proper administration of a CVC benefits
from knowledge of the location of the vessels of interest.
[0006] It is therefore useful to develop methods and systems for
accurate location and imaging and detection of vessels, especially
to assist in medical diagnoses and procedures that employ the blood
vessels such as in the applications mentioned above. It would be
especially useful to overcome present limitations and provide
systems that combine accuracy, clinical relevance, comfort, and at
the same time are relatively inexpensive, reliable, and not
excessively cumbersome. This disclosure addresses some or all of
these issues.
SUMMARY
[0007] The present disclosure relates to visualization of things
and features within objects. Generally, for example, the
measurement of data beneath a surface, and then the display or
projection of the measurements onto the surface. This can include
in some examples subsurface temperature maps, blood vessels, oxygen
or other gas content beneath the skin and so on. In an example,
this includes visualizing fluid conduits within solid objects or
visualizing blood vessels (veins and/or arteries) within human
bodies. In some respects the disclosure relates to the operation of
the vascular system, e.g. in humans, but also in other animals,
specifically addressing aspects of the imaging, detection and
treatment of a patient condition by way of the vascular system.
Existing systems that attempt to do so are excessively cumbersome,
costly, ineffective, and not portable enough to be effective for
all applications.
[0008] The present disclosure provides systems and methods for
imaging and display of features of a region of interest, for
example but not limited to, a portion of a body of a patient. A
first imaging portion of the system is used to cause an interaction
of an imaging beam with an underlying feature of a region of
interest. A reflected or returned portion of said imaging beam is
detected by a detector which then provides an output to control a
display portion of the system for displaying an image corresponding
to that which was detected. The system can be used for guiding or
assisting clinical operations or for diagnosis of medical
conditions and other uses within medicine, industry and others.
[0009] One particular embodiment is directed to an imaging system
for imaging a region of interest, including an imaging light source
providing an imaging light beam including light in a first range of
the electromagnetic spectrum, an incident portion of said imaging
light being suitable for optical interaction with an underlying
feature of said region of interest and suitable to provide a return
portion of said icing light following an optical interaction of
said imaging light beam with said underlying feature; a detector
adapted and arranged to detect a magnitude of a characteristic of
said return portion of said imaging light and adapted to provide an
output signal corresponding to said magnitude; a display light
source providing a display light beam including light in a second
range of the electromagnetic spectrum, the display light beam being
suitable for projecting an image onto a surface of said region of
interest; a controller adapted and arranged to receive the output
signal from said detector and provide a control signal to control a
characteristic of said display light beam; and a scanner for
scanning said imaging and display light beams across said region of
interest.
[0010] Another particular embodiment is directed to a method for
detecting and generating a visual representation of a feature
beneath the surface of an object, including generating an imaging
light beam; controllably scanning said imaging light beam across at
least a portion of said surface; detecting a characteristic of a
returned portion of said imaging light beam which has interacted
with said feature beneath the surface of the object; generating a
control signal corresponding to a characteristic of said returned
portion of said imaging light beam; generating a display light beam
and modulating a characteristic of said display light beam using
said control signal; and controllably scanning said display light
beam across at least said portion of said surface so as to visibly
represent said feature on said surface of said object.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates an exemplary system for sensing and
displaying subsurface blood vessel structure;
[0012] FIG. 2 illustrates an exemplary response curve for
oxygenated and non-oxygenated blood as a function of wavelength of
incident light;
[0013] FIGS. 3 and 4 illustrate yet other exemplary systems for
subsurface feature sensing and display; and
[0014] FIG. 5 illustrates an exemplary scanning pattern.
DETAILED DESCRIPTION
[0015] FIG. 1 illustrates an exemplary embodiment of a measurement
and display system 100, which measures or detects some feature
beneath a surface (e.g., skin surface) and displays information
onto the surface indicative of the measurement. The system includes
an imaging laser 102, which provides a coherent laser light output
in an appropriate frequency range for imaging a feature beneath the
surface, for example, the vascular system 113 in a patient's
forearm 130. The system also includes a display laser 104, which
provides a coherent laser light output in an appropriate frequency
range for display of an image, typically in a visible range of the
electromagnetic spectrum (i.e., having a wavelength between about
400 and 700 nm). The imaging laser 102 is generally used to obtain
the location of the vessels of a patient, while the display laser
104 is generally used to indicate to a medical practitioner or user
of the system 100 the location of the imaged vessels. In some
embodiments, the location of the imaged vessels is substantially
overlaid in a projection by display laser 104 onto the body of a
patient so that the projected image of the vessels is outlined onto
the surface of the patient's body (skin) and generally maps to the
actual location of the vessels below the surface. In this way, a
practitioner (surgeon, blood technician, emergency injection
operator, etc.) can easily locate the vessels below the surface of
the skin and access the vessels as necessary, with the desired
accuracy, to accomplish their task. As will be explained below, the
present system can also be used to detect and project information
about temperature, oxygen content, and other measurable
features.
[0016] One or more rotating mirrors 106 are used to direct the
light output of the imaging and display lasers, 102 and 104
respectively, onto the desired location of the patient's body. Note
that the rotating mirrors 106 can be augmented with other optical
components such as other lenses, gratings, optical elements,
apertures, gates, relays, mirrors, including flat, concave, convex,
or combinations thereof to achieve the desired guidance of the
light onto and collection of light from the patient's body. The
illustration is intended to depict an optical assembly generally,
including a combination of the above types of components or others
as would be appreciated by those skilled in the art. This can
include focusing or defocusing elements, filters, amplifiers, and
other optical components as called for in a particular design of
the system 100. The overall result of the one or more optical
elements is an optical assembly that provides an imaging beam 103
by which the patient is irradiated and which is incident upon a
region of interest ("ROI") 110 of the patient's body. One method of
achieving the transmission of the incident beam over a rectangular
ROI 110 on the skin is by means of a pair of mirrors which rotate
in orthogonal planes and which redirect the laser beam in a
controlled raster-scan pattern over an x and y coordinate axis
projected onto the skin as will be described below. The imaging
beam 103 operates on and interacts with the patient's vasculature
and/or blood and provides the imaging of the vascular system in the
ROT 110. In addition, the optical assembly (or a separate optical
assembly if the aging and display paths are treated separately)
carries a display beam 105 that is used to display the relevant
image of the vascular system of the ROI 110. In some embodiments,
the display beam 105 and imaging beam 103 propagate along parallel
but spatially distinct optical paths. In other embodiments both the
display and imaging beams 105, 103 propagate substantially along
the same optical path and use shared optical components.
[0017] In operation, the imaging beam 103 is incident upon a ROT
110 on the patient's body as mentioned above. The light from the
imaging beam 103 penetrates the patients skin and outer tissues so
as to be incident on and interact with the patient's vascular
system and/or the blood within the patient's vascular system in the
ROI 110. The light from imaging beam 103 is then redirected,
reflected, refracted, and otherwise sent upon its interaction with
the patient's vascular system and/or blood in the ROI 110 back out
from the patient's body in what we refer to herein as the
"reflected imaging beam" 107. In one embodiment, near-infrared
light is used which is known to have a higher absorption
coefficient by blood than by other tissue. It should be appreciated
that while reflection and absorption is one way of forming the
reflected imaging beam 107, other optical and electromagnetic,
chemical, and mechanical effects influencing the incident imaging
beam 103 can also contribute to or influence the light forming the
reflected imaging beam 107. The intensity of the reflected beam is
a function of the absorption and scattering of the incident beam by
the tissue and blood upon which it is incident at each location in
the ROI as the incident beam is controllably scanned across the
ROI.
[0018] The reflected imaging beam 107 is sensed by a photocell 108.
More specifically, light forming the reflected imaging beam 107 is
collected by some optical assembly that can include a lens,
collator, filter, modulator, mirror, prism shaped collector, and
other optical elements for delivery to a photocell 108, directly or
indirectly. The photocell 108 can be of a number of sizes and
configurations so that it can sense an intensity, power, amplitude,
or other quantifiable characteristic of the reflected imaging beam
107. Photocell 108 may include an array or grid of photo-sensitive
elements, e.g. arranged in two dimensions such as x-y Cartesian
dimensions to form an output signal 109. When measured by a
photodetector as a function of time (which can be directly related
to the position of the incident beam in the ROI as it is scanned
across the region), the signal intensity from the reflected beam
can be used to recreate a map of the tissue reflection and
absorption as a function of location in the ROI. Note that in some
embodiments, the use of a line-source or spot/pencil beam source of
light can be accomplished where the line or pencil beam sources are
scanned with a mechanical or opto-electro-mechanical scanner so as
to cover the surface of the ROI by translating the location of the
spot or line beam over the surface of the ROI.
[0019] In turn, the photocell output 109 includes one or more
signals that can be used to modulate the display laser 104 and
hence modulate display beam 105. It can now be seen that the
display portion of the system 100 is modulated by the imaging
portion of the system 100 such that the images projected by the
display portion of the system 100 can include information derived
from the imaging portion of the system 100. In particular, in some
embodiments, the display portion of the system 100 can be made to
project an image of or light information representative of the
blood vessels in the ROI 110. Even more particularly, a visible
light image can be projected onto the surface of the patient's body
that is effectively a representation that is spatially and visually
matched to or corresponding to the blood vasculature beneath the
ski in the ROI 110, where a light-coded portion of the projected
image corresponds to an underlying vessel located directly beneath
the light-coded portion of the projected image.
[0020] In one embodiment, the intensity of the projected display
light beam 105 is modulated to spatially indicate on the patient's
body in the ROI 110 the location of an underlying vein (or vessel
that is to be injected or otherwise used in a medical procedure
such as insertion of an IV line. In another embodiment, the inverse
image (the negative) is possible, where the path and location of a
blood vessel is darkened relative to the surrounding portion of the
ROI 110. In yet another embodiment, a color-coding is used in a
multi-color modulated display system to indicate various features
of the vascular system being imaged. For example, characteristics
of the vascular system including temperature, flow rate, oxygen
level diameter, pressure, proximity to the surface, and other
characteristics of the vessels and vascular network can be
indicated by proper modulation of the imaging portion of the system
100.
[0021] As to the design of the rotating mirror assembly 106, this
allows single line or planar scanning of a region of interest over
a finite surface of the patient's body so that a single and
relatively simple laser can be used for the imaging laser 102. In
the same way, a relatively simple source can be used for the
display laser 104 so that it can be used to cover and illuminate
and form a projection onto a finite area of the ROI 110 of the
patient's body. The operation of the rotating mirror can be
controlled so that its speed of rotation allows a pulsed or
continuous application of the laser sources 102, 104, to achieve a
controlled result on the patient's body in the ROI 110. In one
embodiment, the image and display lasers use the same rotating
mirror assembly to minimize the number of parts and to ensure
perfect collocation of the two laser beams on the ROI.
[0022] The display laser 102 itself can also be made of one or more
parts so as to project an image (e.g., a two-dimensional image) or
representation upon the patient's body's ROI 110. The display
portion of the system 100 can be specifically built to include a
microdisplay, digital projection elements, micro-reflectors, etc.
that are controllable and addressable to form two-dimensional light
output in display beam 105 that is indicative of the vascular
structure being imaged. The modulation of the display portion of
the system 100 can be amplitude modulation with a resulting
dark-to-bright modulation of specific areas of the illuminated
image corresponding to characteristics of the vascular system in
the patient's body in the ROI 110.
[0023] In some embodiments, the system may comprise a low-power and
hand-held apparatus within a compact housing 101. This application
can be used in the field for military (e.g., combat) or civilian
(e.g., emergency services) operations to locate blood vessels below
the surface of a patient's skin under various conditions.
[0024] The system 100 can be portable, light-weight and powered by
a DC power source such as a battery. A visible projected cross hair
marker 111 or other marking can indicate to a user a location of
interest on the surface of the skin (or other surface). For
example, this marker can be projected on a location of a vein for
the purpose of inserting a needle or catheter at this location of
interest.
[0025] A region of interest ROI 110 can be a substantially
two-dimensional surface of a patient's body having any of several
shapes and sizes. For example, ROI 110 can extend in two Cartesian
dimensions along the surface of a patient's body or skin, covering
a substantially rectangular patch or aperture of said body or skin.
Also, ROI 110 can extend in other coordinate systems such as a
cylindrical or polar coordinate system and cover a substantially
circular patch or aperture of said body or skin. Of course, in a
real body, the surface covered by the ROI 110 can be generally
planar (e.g., covering a small region of a human's abdomen) or can
be non-planar and including topology that follows the surface of
the body.
[0026] In some applications, the present system can be used to
determine spatial profiles of thermal or chemical composition maps
beneath a surface, e.g., the surface of a patient's skin. The
information measured can be illustratively depicted or processed
then displayed onto the surface, typically in a visible depiction
overlaid over the region where the measurement itself is made.
[0027] One such application specifically would be for oximetry. As
described above, blood provides a measurable medium due to the
mechanical, optical and chemical composition thereof, and due to
the contrast between the composition and nature of blood (including
hemoglobin) and surrounding tissue. Oximetry measurements can be
made based on infrared and red light wavelength absorption
characteristics of oxygenated hemoglobin in the blood and/or
deoxygenated hemoglobin in the blood. Deoxygenated hemoglobin
absorbs red wavelengths (600-750 nm) more than oxygenated
hemoglobin or other tissues. Oxygenated hemoglobin absorbs infrared
wavelengths (850-1000 nm) more than other substances do. The ratio
of infrared to red absorption in arterial blood correlates to the
ratio of oxygenated to deoxygenated hemoglobin. In practice, these
measurements can be used with lookup tables to determine an oxygen
saturation or relative oxygenation level of the blood. This effect
may be due to the chemical, mechanical, optical, electro-optical or
other physical characteristics of the blood, and is intended here
as an illustrative example of the present concept rather than a
limiting discussion of the same. Those skilled in the art may
appreciate the generalization of the instant description to similar
or analogous uses in such or other materials in living or
non-living organisms and subjects.
[0028] FIG. 2 illustrates a simplified plot 200 showing absorption
210 as a function of wavelength 220. The exemplary absorption
characteristics of oxygenated hemoglobin (HbO2) 230 compared to
deoxygenated hemoglobin (Hb) 240 illustrate how quantitative
determinations can be made for detecting vessels carrying Hb and
HbO2 beneath the skin. For example, a wavelength 202 of 660 nm
would be suitable for determining the presence of Hb while a
wavelength 204 of 910 nm would be suitable for determining the
presence of HbO2. Our imaging wavelength can detect one or both of
these and our display wavelength can project a graphical
representation of the vasculature on the surface of the skin
substantially congruent to the physical location at which each of
these things has been detected. Furthermore, a quantitative
representation can be made so that the projected or displayed
information shows the oxygenation level where this quantity has
been measured. The amount of oxygen can be shown by a color coded
projection or by projection of characters (e.g., numbers) onto the
surface of the skin of the patient showing the same. In an example,
the wavelength interacting with Hb is between 500 and 800 nm,
optimally about 660 nm and a second wavelength interacting with
HbO2 is between 800 and 1100 nm, optimally about 910 nm.
[0029] In an aspect, a combined laser path imaging system as
described herein can be used to measure the ratio of absorption of
infrared and red laser light at given locations in a region of
interest, for example, on a point-by-point basis. The region of
interest can be an antecubital fossa where several large blood
vessels are present. Current vessel location systems require
contact measurement apparatus, typically using the transmission of
LED light in two selected wavelengths to calculate the oxygen
saturation. However, the present system allows for a
multi-wavelength compact (and sometimes portable or even hand held)
device that can operate without contact to efficiently locate and
display features below the skin surface. Again, this system and
technique can be generalized to other surfaces such as walls or
objects concealing subsurface features.
[0030] FIG. 3 illustrates an exemplary system 300 for detecting and
displaying measurements relating to a subsurface characteristic
such as blood oxygenation information (oxymetry), which can be used
to determine the state of hemoglobin as a function of location in a
region of interest. This information can be of clinical value and
can be used in imaging or other diagnostic and therapeutic
procedures.
[0031] In this and other embodiments, computer technology,
generally including processing hardware, software, firmware or
other machine-readable instructions can be utilized to control the
operation of the system. Those skilled in the art will understand
various implementations of the present system that include such
processing hardware and program instructions, some or all of which
can be procured from components known in the art, but which are
creatively now coupled and programmed and arranged as presently
described. Uses of such technology can be made in the user
interface designs for the present systems. For example, to allow
entry of information and other desired settings and configurations
of the system. Then, to allow for reading or receiving output from
the system as needed. Interfacing the system to other machines is
contemplated, including connecting the system through appropriate
connectors and interface units to computer data networks, database
systems, healthcare provider computer networks, insurance data
systems, and other processing systems and networks. In addition,
signal processing and data acquisition and filtering and related
operations can be achieved through similar computerized
functionality as would be known to those skilled in the art in view
of the present disclosure. Hence, generally, a signal processing
unit 302 is provided to achieve the above functions. Note that this
functionality can be contained in a single general purpose or
special purpose hardware or computer chip or processing circuit, or
it may be divided among a number of circuit components and
processors that cooperatively achieve the same end.
[0032] The other elements of system 300 are similar to that
described above. For example, a plurality of laser sources
operating at respective wavelengths are provided for the present
imaging and display functions, including to investigate the
presence and location of oxygen rich and oxygen poor hemoglobin in
blood vessels beneath the skin (using, e.g., red laser 310, display
visible laser 330 and infra red (IR) laser 320). These laser beams
322 are scanned across a region of interest, the imaging (or
sensing) beams of which penetrate the skin surface to investigate
what lies below, but the display laser beam 332 scans over the
corresponding skin locations to show the user where the items of
interest lie beneath. As mentioned, rotating mirrors 306, which
generally mean a scanning optical assembly, are provided to scan
the beams across the region of interest. Collector 308 acts to
collect light in the system and direct it to photocell 304. More
than three beams of various wavelengths may be used to further
detect or discriminate sensed objects beneath the surface of the
skin if desired by extending the present concept.
[0033] FIG. 4 illustrates another embodiment of a system 400 for
detecting and displaying information based on sensing the same
beneath the surface of an object but projecting the same onto the
surface of the object. A plurality, e.g., three, laser beams are
provided by respective sources 402, 404 and 406. The beams are
directed by a common beam splitter or combiner 408 to pass through
collector 440 onto rotating mirrors (or optical assembly) 430 and
then to the region of interest 450. The rotating optical assembly
430 may be substituted with a solid state scanning or modulating
assembly. In this embodiment the sensing (imaging) and display
laser beams (from sources 404 and 402 respectively) are collinear
and travel substantially along a common path or parallel pathway
towards the region of interest 450. The scattered or retroreflected
portion of the sensing beam returns to the rotating optical
assembly 430 and is reflected at least in part by the collector 440
towards the photocell 420. Signal processing of the collected
signal from photocell 420 is provided to signal processing unit 410
or other digital data units as discussed above.
[0034] In addition to that described previously, the present system
can be used to accomplish pulse oximetry and improve the system's
signal to noise ratio and eliminate or reduce background signals
from the detected absorption signal. The system can be used to
filter background absorption signals from the venous blood and
other tissues. By tracking the time dependent absorption signal,
the system can sense periodic peaks in absorption due to pulmonary
pulsation of blood into the organ of interest. Periodic rise and
fall of the intensity of the absorption signal can be used to
define a DC absorption floor where background tissue and venous
blood are responsible for the absorbed light rather than arterial
blood. The system can then subtract the background absorption
signal from the measured absorption signal to eliminate the noise
of non-arterial blood absorption to yield a more accurate
measurement of the arterial blood absorption characteristics in a
location of interest. Pulse oximetry also permits measurement of
heart rate as it affects the periodic flow of hemoglobin in the
region of interest through measurements of the red and/or infrared
absorption signals.
[0035] In another aspect, thermometry of tissues can be performed
using the above system and techniques. Specifically, a temperature
map as a function of space or space and time can be achieved. In
fact, using the same architecture described herein, all of the
above measurements and a display of the same can be made in a
patient. FIG. 5 illustrates a simplified raster scanning pattern
510 over a region of interest (e.g., skin) providing pulse oximetry
(PO) 522, heart rate (HR) 524 and temperature (T) 526 at each point
in the region of interest.
[0036] It should be appreciated that the overall operation of the
present imaging and display systems can be controlled by the
construction of the system and by the method for applying the
system to the patient's body. For example, the overall power and
intensity of the imaging beam and the optical wavelengths used in
the imaging portion of the system can affect the physical
characteristics to which the system and imaging light responds. For
example, using other wavelengths, e.g., infrared light, or
near-infrared light, to image the body can provide deeper
penetration into the body depending on the application and the type
of tissue intervening between the light source and the feature
being detected.
[0037] It should also be appreciated that the wavelength of the
imaging and the display light beams do not have to be the same. For
example, the imaging light may be in the infrared while the display
light may be in the visible range of the electromagnetic spectrum,
allowing plain-sight observation of the displayed image projected
onto the ROI. Auxiliary features and functions can be
microprocessor controlled and can include the ability to control
the intensity of the imaging and the display portions of the
system.
[0038] The present system and methods can be applied to more than
just imaging of veins, arteries, and vessels in a human or animal
body. But with proper selection of inking light source power and
wavelength and system design the system can image piping and
vessels and flow paths and other features hidden from view. For
example, for inspection of circuit boards, fluid pipes, wear on
parts, or other thermal or corrosive environments best imaged with
ultraviolet ("UV") or infrared ("IR") or other light sources. A
light source optimized in frequency and other characteristics to
image the feature or object disposed below the skin or skin and
subcutaneous fat layers or other tissue can be used.
[0039] In addition, there can be safety and architectural and
manufacturing applications of the present systems and features. In
addition to those already discussed such as IV and central line
placement, some specific applications which the present system can
be adapted for include: infrared ("IR") spectroscopy for chemical
identification and blood analysis, for glucose and metabolic
monitoring, for treatment of bleeding patients or those having
internal bleeding, intraoperative use to avoid unwanted cutting of
blood vessels during surgery, dermatological use for assessing
ulcer vascularization and other possible uses of IR or UV signal
from the skin to assess melanoma, differentiate malignant/benign,
assess skin health from sun damage, deeper thermal imaging of
sinuses in suspected sinusitis to assess for blood, visualizing
varicosities and other telangiectasia of the venous system. In
addition, the system could be adapted for use in biometric security
applications such as personal identification and secure access
applications where a unique or detectable blood vessel or pattern
of blood vessels or other biometric characteristic is sensed and
indicated.
[0040] Numerous other embodiments, modifications and extensions to
the present disclosure are intended to be covered by the scope of
the present inventions as claimed below. This includes
implementation details and features that would be apparent to those
skilled in the art upon review of the present disclosure and
appreciation of the concepts and illustrative embodiments provided
herein.
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